Elastic lignin compositions



United States Patent The present invention relates to a process for thepreparation of new elastic lignin-containing compositions by the admixture of lignin sulfonic acid constituents from waste suliite liquors with natural rubber, synthetic rubber,

polyvinyl chloride and mixtures thereof or the like prodnot, in which mixture the lignin substance contains about l0-30% of liquids which disperses and dissolves the'lignin sulfonic acid in colloidal and molecular distribution to facilitate the homogeneous blending thereof with the rubher substance, said mixture being worked-up at elevated temperatures in a rubber kneader or on calendering rolls,

in the manner as is usual with the working-up of rubber masses.

'With an accurately limited liquid mixture of 10%to at most in the composition of the invention, the H 1 neutral lignin sulfonic acid, acidified lignin sulfonic acid and a calcium oxide free alkali salt of lignin sulfonicracid is brought into such a physical state that it can be worked in the form of a molecular or colloidal subdivision into the rubber or synthetic elastic mass in the rubberkneading apparatus to provide a completely homogeneous p'roduct with improved properties as compared with the conventional rubber and synthetic rubber mastication process and product. The calcium oxide free alkali salts of .lignin sulfonic acid, hereinabove described, consists of the .sodium, potassium, ammonium and calcium lignin sulfonates which are purified to remove calcium oxide so that the salts contain less than 1% of calcium oxide calculated relative to the dry substance; the neutral and acidified lignin sulfonic acids are likewise purified in this same technical lime'free sense so that they each likewise contain less than 1% of calcium oxide calculated relative to the dry substance.

The heat liberated in the mastication of the rubber component prior to skin formation suffices to soften the lignin component in the composition of the invention and assists the homogeneous incorporation of the lignin com, ponent into the rubber. The lignin mass introduced into the elastic component, because of its very fine state of subdivision, exerts an unexpectedly strong dispersing :action and serves as a rubber economizing auxiliary in the formulation of the desired elastic product. The lignin component may be used in quantities up to 100% by weight of the rubber, synthetic rubber, polyvinyl chloride or the like, or in mixtures thereof. The liquid serving as solvent and dispersant for the lignin sulfonic acid is water, or lower alcohols, such as methanol, glycerol, glycols such as ethylene glycol, diethylene glycol, propylene glycol and butylene glycol, or formamide, =or mixtures of these organic solvents with each other and/orwith water. -Acid additions may be made to the solvent, such as phosphoric acid, sulfuric acid, acid salts such as aluminum sulfate, water soluble organic acids,=-and organic acids soluble in the other solvents employed, i..e-. formic, acetic and in some cases glycollic acid.

It has already been proposed, in Germany, to admix waste sulfite cellulose liquor lignin in the form ofa'powder with a water content of about 5%, with rubber as a filler therefor. Attempts of this type could-not-,succeechwsince even the 'dried waste sulfite liquor lignin, regardless .of whether it came from roller driers or'atomizing'jdriers,

2,760,943 Patented Aug. 2%, 1956 "ice jneverpossesses a particle size capable of giving the desired effect in the rubber. An additional consideration is that the lignin of the waste sulfite liquor is infusible, i. e. does not liquefy, even at elevated temperature in rubber or caoutchouc, but instead decomposes at temperatures above 140.

Likewise, it is impossible to work commercial concentrated waste sulfite liquor containing 50-60% of dry substance, into rubber, because of the high water addition.

Better, results are given by the rubber products developed in America from rubber and alkaline, i. e. fusible as well as acidifiable lignin. 'It is known that the surfaces of the'lignin'have insome way to be activated or .altered e. g. by oxidation processes, it the effect of a good filler action in rubber is to be realized. The especial suitability-of alkali lignin is ascribable to this. According to this known process, the lignin, obtained from the socalled black liquor of the alkaline soda process or of the sulfatecellulose process, in solution with caustic soda and water in amounts up to 40%, is admixed with latex milk, and this mixture acidified and precipitated with sulfuric acid.

The lignin sulfonic acid product used in the invention is obtained from fermented or unfermented waste sulfite cellulose liquor, which liquor is a product of the conventional sulfite or bisulfite cellulose decomposition product. The waste sulfite liquor from the conventional paper making process is first neutralized with a base, e. g with liquid or gaseous ammonia, then after concentration, pre

cipitation and the filtration of the lime by the addition of sulfuric acid, the sulfuric acid is neutralized with alkali such as soda to bring it to a substantially neutral pH. The

neutralized lignin sulfonic acid purified in this manner is evaporated to dryness and redispersed and redissolved under stirring and/or kneading with a liquid such as water, alcohols, formamide, etc. at temperatures of at least 4G-100 0, preferably -80 C. to obtaina highly viscous lignin sulfonic acid solution which solidifies at 20 C. to a solid resinous mass.

l he thermoplastic resinous mass obtained by redispersion is added in amounts up to to the rubber cornponent on a masticating roller. It is more'advantageous to work-up the lignin sulfonic acid mass together with the elastic material in a closed rubber kneader to form a batch. Upon renewing the heating duringthis working up of:the"batch, the lignin sulfonic. acid mass becomes quite soft and is taken up by the rubber component in such a state of subdivision as to provide the improved processing andproduct features of the invention.

The rubber component may be plasticized in order to facilitate its blending with the lignin component. The lignin component may be admixed with additional -auxib iaries for specifically desired properties in the final product; the addition of carbon black, alumina gel, plasticizers for the rubber component and materials to reduce the viscosity of the rubber component may be added to the lignin component to improve the processing during the blending operation and to render the incorporation of these materials in the rubber component as superfluous.

The synthetic rubber component which is utilized in the process and product of the invention is a synthetic polymerized diolefine or copolymer thereof such as a butadiene acrylonitrile copolymer, a butadiene styrene copolyrner, an isobutylene butadiene copolymer, :2. chlorinated polybutadiene such as polychloroprene and neoprene, etc.

slightly acid, freed of calcium impurities to eliminate organically bound lime (CaO) and calcium sulfite to obtain a lime free lignin sulfonic acid containing less than 1% CaO, calculated relative to the dry substance, evaporated to dryness and. redispersed in to 30% of a liquid such as water, lower alcohols, glycerol, glycols, formamide, and mixtures thereof with or without water, said lignin material being in a state of colloidal and molecular subdivision so that it is doughy at 4080 C. and solidified at 20 C., the mixture being calendered and masticated at elevated temperature to provide a homogeneous incorporation of the ingredients.

A further object of the invention is the Preparation of a new elastic lignin-containing product wherein the lignin substance identified hereinabove is admixed with one or more fillers and reinforcers such as alumina, lamp black, chalk, zinc, oxide, lubricants such as graphite, etc., plasticizers for the rubbery material, viz. rubber, synthetic rubber, and mixtures thereof, coloring matter such as aniline dyes, and natural resins as additives for the rubber whereby the lignin product acts as a dispersant for the homogenization of the additives with the rubbery component and wherein amounts of the lignin product up to 100% of the rubbery component are used in the milling at elevated temperatures.

A further object of the invention relates to the improvement of the process of manufacture of rubber elastic products and the novel product obtained thereby wherein the lignin component, hereinabove identified, is admixed with one or more of the ingredients, aniline, urea, melamine, albuminous substances, formaldehyde and furfural, which additives react with the lignin in a period of time to condense with the lignin, whereafter the product of said first stage of reaction is homogeneously blended with the rubber component, hereinabove identified, at elevated temperatures above 100 C. in a mastication and calendering homogenizing process which is then followed by a final vulcanizing step. The rubber or synthetic rubber component, as this term is hereinabove defined, is utilized as an aqueous emulsion and the lignin sulfonic acid component is admixed with an aldehyde to condense therewith in order to modify the lignin component to improve its precipitability after the so-reacted lignin component has been blended with the rubber component in the emulsion.

Other and further objects of the present invention will appear from the more detailed description set forth first stage, at temperatures below 100 C. for a sutficient lignin sulfonic acid mass below, it being understood that such more detailed description is given by way of illustration and explanation only and not by way of limitation.

If an acidifiable resinous product from waste sulfite liquor is desired, e. g. for working into aqueous rubber dispersions, then the purified or unpurified lignin substance together with the lignin dissolving liquid, e. g. water, may be reacted with substances which, during the working-up with the lignin sulfonic acid, react with the latter at temperatures below 100 with an increase in the size of the molecules, thus to improve the precipitation and homogenization, and under the conditions of the vulcanization at temperatures above 100 to initiate a final condensation in the insoluble form. Suitable for this purpose are aldehydes together with one or more of steel needle.

this way, only, does a reinforcing or strengthening efiiect appear. For working up lignin sulfonic acid resin with latex, it has been found that use can be made only of lime-free lignin sulfonic acid, in the technical sense hereinabove defined. Sustantial improvement in the strength of the vulcanizate obtained from the homogenizing of a rubber or synthetic rubber emulsion component with the lignin component is attained when the aldehyde reaction product of the lignin component is further reacted with amines and amides such as aniline, melamine, dicyandiamide, urea and other 'arninoplasts. Soluble albumin compounds likewise modify the lignin component to improve the strength of the resulting vulcanizate. The aldehyde reaction product improves the blending quality of the lignin component with the rubber emulsion component. The blending quality is maintained over a Wide range of pH, i. e. about 5- about 8. Y

Admixture of the lignin sulfonic acid, which has been treated with lignin-dissolving liquids, with a natural rubber mixture in an amount of 20%, relative to the weight of the rubber, gives improved technical data in the vulcanizate prepared therefrom, as shown by the following test results for a soft mixture:

A lignin mixture is composed of the following constituents; the parts being parts by weight:

75 parts of calcium ligninsulfonate (lime free), obtained from waste sulfite liquor, pulverized and air-dried 7 parts of formaldehyde (30% formaldehyde by weight) 3 parts of formic acid by weight) 8 parts of water 7 parts of aniline,

are blended to form a lignin sulfonic acid mass. A

The mixture contains the following ingredients (all parts in parts by weight) Mixture Mixture I II a. N o Pos e-P light crepe mercaptobenzothiazole oooenoo Vulcanizati'on2S minutes, 3 atmospheres absolute.

The following comparative values were realized:

Mixture Mixture I II Tear Resistance, kg/em. longitudinal Tear Resistance, kg/crn. transverse Notch Strength, kg/4 mm. of thickness longitudinal- Notch Strength, kg/4 mm. of thickness transverse Hardness according to Shore, Shore degrees Elongation at rupture in percent of original length Specific Gravity The preceding, which deviate considerably from the examples, are not absolute values, but serve only to demonstrate the comparative strength increase upon addition of lignin products according to the invention.

The below described testing values for the examples hereinafter, were determined in accordance with the following procedures:

(a)' Tearing resistance tests (resistance to tearing by needle).-Strips of vulcanizate 20 millimeters wide and 50 millimeters long are bored through at a distance 5 millimeters from the edge with a 1 millimeter diameter The minimum load necessary to tear the strip is determined on a Schopper rubber tearing machine which provides a pulling velocity of 100 millimeters per minute. The strength obtained in the foregoing table indicates the tearing strength on the testing stand ard as measured in kilograms per centimeter. See the procedure in the text by Dr. Paul Klukow, Verarbeitung von- Kautschukj Union .Deutsche-Verlagsgesellschaft as h l i h er. n u minaGcrmany..

to tearis standardized in German DIN 53507 of Novem:

ber 1943; andthe value determined herein, isjbased upon a fan test conducted asset forthin the text hyDr; Pil -ll Kfltikpw; Verarbeitung von Kautschuliff Uni 'ljeutsc'lie- Verlagsgesellschaft Berlin, Rjoth' & Co.';, 19 41,f pag"e 46, 'I hevalues obtained are given in kilograms per4'niillimeters of thickness or may be reported" in kiloglams'peicentimeter of thickness. I

(2:) Hardness" tests.- Hardness. is determinedfin ac-. cordancc with the" spring penetration depth on uiees't body in the method of'ShOregth'e value obtained" iii Shore degrees. I ,I'

(d) Specific gravitye-"Specific gravity was determined as the bouyancy method:

k (j); Elongation at rupture, expressed, as per; cent elongatiorz'i of the original length.--The rubber tearing machine of the firm of Zwick & co ul mrEinsingen was used in accordance with DIN DVM 350'4lus1ing a test specimen form which is a standard rod, StI the rupture elongation equals the percent elongation of the' original length .at the moment of rupture. I V 7 355,-"

An ad ition. up; to 15 of lignin sulfonic acid substance or in some cases more, calculated relative to the weight of the. rubber, is suitable for a rubbershoe sole mixture;.vvhereby thehardness: of: the'vulcanizate is im-.

proved, without impairing the other technical datat; For a floor covering mixture or similar mixtures for. technical purposes, lignin sulfonic acid substance iii amounts up to 40% or in some cases more, also r lated relative to the weight of-the ru'bber', maybeadded in order to obtain a vulcanizate of enhanced hardness. The same is true for rubber seals and other-technical molded rubber articles. .1.

'I lre, admixture of lignin sulfonic acid substance. in amounts of about 10%,.calculated relative tov the weight: of the. rubber,.with synthetic rubber, such, as Perbunan and Bolysar, i e. copolymersyof butadieneand acrylolnitrile, improves the, workability-of the elastic material; such. as, skin formation, absorbability of fillers and. spray-' ability.

The lignin sulfonic acid acts here as a softener; In the co-vulcanization of different: layers of rubber, the added lignin sulfonic acid has a favorable influence on theffibwi'ng together (int'erflow). a v .7; The" following examplesgiven by way of illustration; and not'oflimitation of the invention, show pr "al methods" forjthe' preparation of the new lignin contalnrngl elastic materialoffth e invention and the improvements in; the processing of rubber,'. synthetic rubber', mixtures ther'eof, andthe lilgewith the addition of the ligninlco'mpohe'nt of: the" invention.

EXAMPLE 1 Ferinefnte d neutralized: pine waste sulfite: liquor. 'isg.- con-. centra'ted down to a dry content of, 5.0%v and-is then pul.-- verized by atomization. The-thus-produced lignim S1117? fonic acid substance is treated in the kneader at ternv peratures between 70 and 80 C. by the addition of hydrochloric acid and so much water that a highly viscous lignin sulfonic acid solutionv results which, with. a dry content of 80%, has a pHvalue of. 5.0 and, ,upon c0011; ing) solidifies to alsolid resin-like. mass; one' parteof-v. thismass is perfectly admixed in the rubberkneader-with; one part of natural rubber..

As solvent for li'gnin, use may water, or lower alcohols, e. g. methanol'or glycerol other or with water. Suitable acids comprise,"?atn'or1g others v phosphoric acid, sulfuricacid, a'cid salts; e. g.

be made; in place t?- lyi col, formamide or mixtures of these solvents" wit 'eajch".;

6 played. These" organic-acids include formic; acetic: and glycolhc acid; I v I EXAMPLE 2 Crude aspen waste sulfite liquor, without further pretreatment, is evaporated down to a dry content of 50% and dried ontthero'lle'r dryer.v The lime contentv is lessithajng1%, CaObased on' the dryweight- The thus obtained lign'in s'ulfonic acid-substance is treated in the kn aeer; at temperatures between 705th 80 C.,, by the addition of hydrochloric acid and such quantity of water that a highly viscou's' ligninsulfonic acid results which with agary; content'of 80%, has a pH value of 5.0' and" becomes rigidv upon cooling into the form of aresin'ous solid mass; .One'part' jof'thi's mass can be homogeneously admixed in. the rubber kneader with" one part ofnatiir'al rubber".

- EXAMPLE. 3

vThe sodium. salt,, prepared in. known man'n'r of the lig'ninwsulfonic acid i of a beech waste sulfite liquor is' worked-up, initheuform of powder, by kneading" with glyceroltand formic acid at 60-65 C, intoahighly-vis= cons lignin sulfonic acid solution which contains 84% of dry substance and has a pH value of 5.5. One part of themass; solidifieda't radar temperatureis worked up on therollers with'4 parts of natural rubber, which was just precedingly'masticizedup to skin'formation. After the addition of 0. 1' pa'ft'o'fsulfur, 0.2 part of zinc oxidteahd;

0103' part of VuIl fa-cit"mercaptobenzothiazole i svulcanized for minutes at" 150 C., and there is produced a material of hardne'ss, 60 Shore, and a notch strength' of9 kg./ 4 mm. thickness as measured by the Gcrmanstandar'd procedure DIN 53,507 of November. 3, 1943. Natural rubber vulcanized under like conditions without lignirt sulfonic acid or other added filler has a hardness of only Shore and a notch s trengthof 6 kg./4 mm. thickness.-

The ligni s 'gccbr ingto'Exam I isuworked in the following admixture:

r I v v Parts by weight Butadiene-acrylonitrile mixed polymer 1000' ZincQWh'ite 5.0

Reaction product of mercaptothiazole and diethylamine; Vulkazit AZ, sold by Bayer, Lever- "ku'sen'" 0.6

The. inclusion. of the lignin sulfonic acid mass shows .up as aw good auxiliary in the working-up, inthat the skin I formation, filler absorption and sprayability are enhanced: Thetechnical data. forthe vulcanizate (2.1 atm. for 20 minutes) are as follows:

Tensile strength 5' 168 k'gI/crriF. Elongation'at rupture; in percent" 525%". J Resid. elongation 18%. Modulus or'load in kilograms at 300% elongation ofthe 0ri'ginalflength' 8l kg./c m. Hardness in degrees Shore Shore. Elasticity 41%.

- mensional) as impacted and rebound elasticity. The

DIN sheets correspond to the ASTM sheets'in the United States;v Y

Tensile strength was determined-by German Standard Method DIN-DVM 3504 of November 1938,-"car'rie'd out according. to Schopper-Dalen (Member Handbuch der Kautschuk Wissenschaften, page 610) and the values obtained expressed in kg./cn1.

EXAMPLE 72 parts of the pulverulent lignin-substance obtained according to Example 1 are kneaded in the kneader for 45 minutes with 4 parts of furfnral, 11 parts of water, 3 parts of formic acid and parts of aniline at temperatures between 80 and 90 C., a precondensation taking place, so that a highly viscous lignin solution which solidifies in the cold and has a pH value of 5.5 is formed. One part of this mass is worked into one part of smoked sheets in the kneader and under the same conditions as in EX- ample 2 yields a vulcanizate of hardness in Shore degrees, 71 Shore with otherwise equal technical data.

EXAMPLE 6 The solidified highly viscous lignin sulfonic-acid mass according to Example 5 is up to 3%, calculated relative Y to the weight of the rubber, is worked into the mixture of a protective rubber component of the following composition, in parts by weight:

Smoked sheets Defo 1500 100.00 Activated carbon CK 3 45.00 Zinc white RS 7.50 Lignin sulfonic acid mass 3.00 Sulfur 3.00 Mercaptobenzothiazole 0.90

The vulcanizate (2.0atm., 30 minutes) gave the following test values:

Resistance, tensile strength 267 kg./cm. Elongation at rupture in per- 580%.

cent. Resid. elongation 26%. Hardness in degrees Shore 69 Shore.

Modulus or load in kilograms 99 kg./cm.

at 300% elongation of original length. Elasticity 50% Notch strength 50 kg./4 mm. thickness.

The admixture of the lignin sulfonic acid product shows no disadvantageous effect in ageing tests.

The values for modulus and wear were determined in accordance with the following standard German procedures:

Modulus equals load in. kilograms per sq. cm. at 300% elongation of the original length.

Wear equals mm. of Worn (or ground oft) material from the nlbber test body under loads of 1 kg. and of 5 kg. on a rubbing or grinding path of 40 m. with a standard lubricant, so that two corresponding values are obtained.

This test is carried out onthe wearing or grinding machine made by Schopper, Leipzig, according to the German standard Patent No. 53,506.

EXAMPLE 7 A lignin sulfonic acid mass for shoe sole mixtures contains the following ingredients, in parts by weight:

69 parts of calcium ligninsulfonate powder, air-dried,

special light (CaO free) i 7 parts of formaldehyde, 30% Y 3 parts of aluminum sulfate, dissolved in 10 parts of water 7pa ts tai n acid, which-are lime-free.

The incorporation of'these ingredients to effect the dissolution ofthe lignin is carried out at 20. A shoe sole mixture in parts by weight prepared with addition of this lignin mass consists of:

Smoked sh 100.00 Natural resin (gum colopony) 2.50 Phenylcyclohexyl-p-phenylenediamine 1.00 Lignin sulfonic acid. mass 10.00 Fibrous material, waste textile powder 32.50

Coloring material, inorganic pigment 11 .75 Filler, finely divided calcium carbonate or calcium The technical data of the light brown shoe sole sheet, vulcanized at 130 C. for 8 minutes are as follows:

Wean for 1 kg. load (only) 250 mm. according to DIN Vornorm 53513 of March 1943 loss in weight 200 a Wiaar m density 4X angle of seizure- For density see DIN 53550.

Hardness in degree Shore. 83 Shore. Tear resistance -c- 30.5 kg./cm. Dynamic flexure at 30,000 blows in 5 hours 0 Tensile strength 59.8 kg./cm.

No deleterious effects apparent during ageing tests.

The artificial ageing of soft rubber is tested according to DIN-DVM 3508 of February 1939. The test pieces were stored either in a heating chamber for about 7' days or even longer at 70il C., or were exposed for 48 hours or even longer to the action of oxygen at 20:05 atm. abs. and 60i1 C. and the changes thereupon ascertained.

EXAMPLE 8 Thelignin sulfonic acid mass according to Example 7 is incorporated, in a rubber kneader, into a floor covering mixture in amounts of 30%, calculated relative to the weight of the rubber, and sheets are produced, after vulcanization, of a Shore hardness up to 92 Shore and with adequate dynamic resistance to bending.

The dynamic testing is carried out with test pieces of 15 mm. width, mm. length and 3.5 mm. thickness on a EXAMPLE 9 V A lignin sulfonic acidmass, lime-free, from pine waste sulfite 1iquor,which is suitable for coprecipitation with rubber emulsions, has the following composition, in parts by weight:

72 parts of sodium lignin sulfonate powder (lime free) 15 parts of formaldehyde (27% by weight) 6 parts of caustic soda solution (25% by weight) 7 parts of aniline.

v.In place of the sodium lignin sulfonate, it is also pos sible to use the ammonium salt or the free lignin sulfonic The ingredients are stirred at temperatures between 80 and 90, precondensation taking place, and are then allowed to cool into a transportable form. 100 parts of the lignin mass in 600 parts of water are brought to a concentration of 34% NHs by the addition of ammonia at 60 and, after cooling, admixed with 166 kg. of 60% latex. By addition of aluminum sulfate solutions, there is obtained, in an ideal state of subdivision, a mixed rubber coagulate, which consists up to 50% of lignin sulfonic acid product. The lignin sulfonic acid-rubber emulsion can also be used, in suitable concentration, as a binder for leather and other fibrous materials. The hardening of the li nin sulfonic acid mass, which causes a reinforcement of the rubber, does not take place until the vulcanization at temperatures from 140 C.

EXAMPLE The lignin sulfonic acid mass according to Example 9, brought into a dry, comminuated, easily handled form, is dissolved up to about in hot water. The cooled solution is used for the preparation of leather fiber plates, as follows: 100 kg. of leather fibers, consisting of vegetable-tanned material, are mixed in a hollander mixer with a large quantity of water. Then a mixed binder solution is prepared, consisting of: 10 kg. of rubber dry-substance in the form of a dilute natural rubber latex and 5 kg. of transportable lignin sulfonic acid mass in the form of the above solution.

This mixed solution is added to the fiber pulp and is stirred. Then the binder is precipitated on the fiber with the usual quantity of aluminum sulfate solution and, finally, the conventional amount of a softening oil plasticizer (oil sulfonate mixture which acts as a softening agent as well as a Wetting agent) is added. After renewed mixing, the fiber is deposited on 4 plate sieves and freed of water. The pressing and drying of the plates takes place in the usual way. The obtained leather fiber material gives, as regards tear resistance and water absorption, the same values as a material prepared with 15 kg. of pure rubber dry-substance in the form of latex per 100 kg. of leather fibers, but gives higher needle tear resistance and a sole-like form of sheet or plate. It is excellently suited for the manufacture of caps.

What is claimed is:

1. A normally solid lignin composition comprising a lignin component containing less than 1% free calcium as calcium oxide, obtained by evaporating to dryness waste neutralized sulfite liquor, freed from calcium oxide, and by redispersing in, from 10% to 30% by weight, a liquid selected from the group consisting of water, lower aliphatic alcohols, and aqueous lower aliphatic alcohols, said lignin composition being doughy at 40-80 C. and solid at C. and adapted to disperse up to 100% by Weight of a rubber component selected from the group consisting of natural rubber, butadieneacrylonitrile polymer, butadiene-styrene polymer, butadiene-isobutylene polymer and chloro butadiene polymer.

2. A normally solid lignin composition comprising a lignin component containing less than 1% free calcium as calcium oxide, obtained by evaporating to dryness waste neutralized sulfite liquor, freed from calcium oxide, and by redispersing in, from 10% to 30% by weight, a liquid selected from the group consisting of Water, lower aliphatic alcohols, and aqueous lower aliphatic alcohols, said lignin composition being doughy at 40-80 C. and solid at 20 C. being dispersed with up to 100% by weight of a rubber component selected from the group consisting of natural rubber, butadiene-acrylonitrile polymer, butadiene-styrene polymer, butadiene-isobutylene polymer and chloro butadiene polymer.

3. A normally solid lignin composition comprising a lignin component containing less than 1% free calcium as calcium oxide, obtained by evaporating to dryness waste neutralized sulfite liquor, freed from calcium oxide, and by redispersing in, from 10% to 30% by Weight, a liquid selected from the group consisting of water, lower aliphatic alcohols, and aqueous lower aliphatic alcohols, said lignin composition being doughy at 40-80 C. and solid at 20 C. and modified by heating at from 100 C. with a minor amount of a hardening agent consisting of a mixture of a lower aldehyde and a material reactive with said aldehyde selected from the group consisting of aniline, urea, melamine and soluble albumin and being dispersed with up to by Weight of a rubber component selected from the group consisting of natural rubber, butadiene-acrylonitrile polymer, butadienestyrene polymer, butadiene-isobutylene polymer and chloro butadiene polymer.

References Cited in the file of this patent UNITED STATES PATENTS 2,077,884 Howard et al. Apr. 20, 1937 2,161,749 Samarus et a1. June 6, 1939 2,266,265 Rieche Dec. 16, 1940 2,365,599 Schirm Dec. 19, 1944 2,377,709 Meunier June 5, 1945 2,387,619 Seidel Oct. 23, 1945 2,443,889 Bruce June 22, 1948 2,491,832 Salvesen et al Dec. 20, 1949 2,533,632 Salvesen et .al Dec. 12, 1950 2,542,344 Mersereau Feb. 20, 1951 OTHER REFERENCES Rubber Age, September 1945, page 701. 

1. A NORMALLY SOLID LIGNIN COMPOSITION COMPRISING A LIGNIN COMPONENT CONTAINING LESS THAN 1% FREE CALCIUM AS CALCIUM OXIDE, OBTAINED BY EVAPORATING TO DRYNESS WASTE NEUTRALIZED SULFITE LIQUOR, FREED FROM CALCIUM OXIDE, AND BY REDISPERSING IN, FROM 10% TO 30% BY WEIGHT, A LIQUID SELECTED FROM THE GROUP CONSISTING OF WATER, LOWER ALIPHATIC ALCOHOLS, AND AQUEOUS LOWER ALIPHATIC ALCOHOLS, SAID LIGNIN COMPOSITION BEING DOUGHLY AT 40* -80* C. AND SOLID AT 20* C. AND ADAPTED TO DISPERSE UP TO 100% BY WEIGHT OF A RUBBER COMPONENT SELECTED FROM THE GROUP CONSISTING OF NATURAL RUBBER, BUTADIENEACRYLONITRILE POLYMER, BUTADIENE-STYRENE POLYMER, BUTADIENE-ISOBUTYLENE POLYMER AND CHLORO BUTADIENE POLYMER. 